Nonhalation photographic film



A. D. sLAcK NONHALATION PHOTOGRAPHIC FILM Fild Feb. l18, 193].

Em Mandami www @y lll ltd

lPatented Apr. 1936.

UNITED- STATES .PATENT f rosario .NoNHALATIoN rnoroonsrnre r Alfred n. slack, noemden', N. r., assigner to Eastman Kodak Company, Rochester, N. Y., a? corporation of New Yon-lr Applicationhebruary ld, lltltl, Soldat No. llltlt ri elaine.

sound recording on nlm, results in improved tone reproduction.

`lillalation and its troubles are well known to those versed in the photographic art, but its prevention or reduction involves a problem.

which has presented many dimculties.

Motion picture film, when developed alter exposure, is customarily processed in machines.

through which it is passed continuously. When some medi has been incorporated in or on the nlm as a means of eliminating or reducing halation, it is accordingly undesirable that this non-halation layer shall become guinmy and sticlr to the gears or loul the developing baths. lt is also deleterious if thislbaclring shall be removed in coherent lms or scales. Such. large pieces or particles 'are apt to become attached to the sensitized emulsion face ot the film. and thus interfere with the normal action or the processing baths.

order to avoid certain ol such dimculties a non-halation layer should either be completely soluble or destroyed in one or anyof the photo graphic baths, or be removed in such sized particles as -to obviate any danger ol interference with normal processing. ln those instances where a dyestud has been utilized as the nonhalation medium, it is furthermore undesirable to use a dyestu which will' be soluble in Yany oi' the photographic baths. Such a coloring ma terial would be released into the baths and tend 4to stain either the emulsion or the base of succeeding film as it passes through the processing It dyestuds are applied directly to the material comprising the hlm support, the dyes utilized y or may not be solubleA or diluted with solvents which penetrate the support, at least sumciently to give the dyes firm adherence. If these dyes be water soluble, or soluble in the normal baths a staining of the emulsion or base may occur as related above. However, if dyes which are not soluble in water or the photographic baths or destroyed in the regular proc-'- baths are used. they are usually dimcult :material and. there is their applied a dyestuid (or. oer-e .of complete removal, although they niay be rernoved by special bleach baths.

Ii a completely water soluble insulating layer or carrier for the non-halation layer or dye he used, it has the disadvantage of becoming soft under moist atmospheric conditions.

.- l overcame all ot the above ditdculties by utilizing as an insulating layer a layer ot mate# rial which is insoluble in water and therefore does not tend to become soft or sticlry under moist cr damp, atmospheric conditions. How ever, the material is completely soluble in an alkaline bath, such as that which comprises the normal photographic developing solution. While this material may be permeable to. or somewhat ahsorptive of water, it is not attacked 'by those solvents ordinarily utilized for the usual cellulosic support.

l It a nlm support be coated with a layer ol' such 2li insoluble ln the photographic baths, from a solvent which does not penetrate through the said layer into the film base,v the dye will remA main as a very thin coating directly over and on the backing layer. rlhis layer thus edectually prevents the dye from reaching the material of the support.

When such a film is processed, the developer permeates the outer dye layer and attacks the insulating layer of casein which is completely dissolved in the alkaline developer and will thus necessarily be removed from the lm support, carrying the overcoat dye layer with it, leaving the nlm base clear and stainless. Moreover, as the dyestu is insoluble both in the water and any ol the normal processing baths, it will neither attack nor stain either the film base or used alone or mixed together as desired.

lf a carrier layer which is not so impervious to water as the above mentioned materials is found suitable .for the purpose desired, other substances may be used. Such materials are dextrose, gum arabic, or other similar' water soluble substances.

However, I have found casein to be particular- 1y desirable. The type of casein which l employ is soluble in glacial acetic acid and may be diluted to'any consistency with ethyl alcohol or other alcohols. lf an acetic acid-casein solution is not desirable, an alkaline solution ol casein may be used. The casein is not water soluble, though as lil.

. the layer.

a layer of it may be somewhat permeable tol water. It is, however, completely soluble in an alkaline bath, although its solubility in the baths may be decreased if desired by the addition of formalin, hexa-methylene-tetramine, certain metal salts or the like.

In `order to incorporate all of the above mentioned desirable features in a non-halation backing, a layer ofthe casein is coated upon the lm base. To this coated layer there may be applied a suitable dye or combination of dyes,

which are not soluble either in water or the developing baths, but are soluble either in a material which is a solvent of the film support or at least penetrates the support. While a mixture of complementary dyes is often utilized in compounding an anti-halation backing with fairly good success, I have found, that, for optimum quality, a black dye is most desirable. As a panchromatized emulsion (which is sensitive throughout the visible spectrum) is now irequently used, a backing material which is about equally absorptive to light throughout the visible spectrum is ideal. In such a case a blue black dye may be perfectly satisfactory as the sensitizing dye incorporated in the panchromatic emulsion so eifectually absorbs light in theblue portion of the spectrum, that the resulting effectual anti-halation qualities closely approach those of a pure jet black.

The ideal dyestuff to use would be one whose absorption most nearly approaches that of carbon.

Typicalsolvents for such dyestuis are amyl acetate, ethyl acetate, carbon tetrachloride, ethyl' alcohol, acetone, or ethylene dichloride etc. 1f it be desired that the dyes shall penetrate more or less into the backing layer, without, however, saturating it to such an extent as to stain the support, t'ils may be accomplished by including with the dye solution a higher alcohol or other material which will prolong the drying time and thus increase the degree of dye penetration into Water may also effectually be used to accomplish this end. If 5% of water be used, a partial penetration can be obtained, and with a larger percentagel any degree of penetration can be procured to the extent even that the lm base itself may be stained.

Ii it be found that the resultant backing is too brittle for normal use,'flexibilizers such as glycerin, rubber latex, triacetin, or other materials may be added. These will be completely removed from the base at the time of processing.

Typical formulae for the insulating layer are as follows:

Typical dye solutions which have been foun useful are the following:

on red o 50 grams Oil blue B 50 grams Ethyl acetate 3500 c. c.

Spirit nigrosine R 50 grams Ethyl alcohol 1900 c. c.

Water may be added to the last formula, the amount added being dependent on the extent to which it is desired that the dyestui shall penetrate the insulating layer. I have found c. c. to be satisfactory.

m order to make the invention clearer, reference is made to the accompanying drawing in which:

Fig. 1 is a section of a film constituting a preferred embodiment of my invention.

Fig. 2 is a section of another embodiment, and

Fig. 3 is a section of still a third embodiment.

The support 2 is of a composition such as is customary for this purpose, usually comprising cellulose nitrate, acetate, ether or other derivative. It has on one surface a photographically sensitive layer l. The water permeable layer is designated as 3 and the dye layer as ll.

If the dye is caused to penetrate the permeable layer as in Fig. 2 it may cease to be distinguishable as a separate layer and there will result a unitary layer 5 which is heavily dyed at and near its outer surface and of graded dye intensity decreasing with the depth of the layer.

The support need not be a single unitary layer but may comprise several permanent layers. The main support may carry a secondary surface layer for anti-static or non-curling purposes.. Such secondary layer would be of a composition diierent from the main support layer, but permanently adherent thereto under all conditions and usage. It may for instance be of a cellulosic derivative different from the main support or it may be of hardened gelatine, hardened casein, an insoluble or hardened gum or other material. In such a case a governing factor will be the anty of the insulating layer or the solvents carrying it for this secondary support layer. Such an embodiment is illustrated in Fig. 3 wherein the main support layer 2 carries on one surface a sensitive layer I and has permanently adherent to the other surface a secondary support layer 6 over which is the insulating layer 3 which protects the layer 6 from the dye layer 4 or the solvent used in applying the dye. When the 'lm is processed, the layers 3 and 4 are removed leaving a clear and unstained support. 4

It is to be understood that I contemplate as included Within my invention all such modifications and equivalents as fall within the scope of the appended claims.

What I claim as new and desire to be secured by Letters Patent of the United States is:

1. A photographic film comprising a light transmitting, flexible support, a photographically sensitive layer on one surface thereof and a halation reducing backing on the other surface thereof, said backing comprising a carrier and a dye, predominantly at the outer surface thereof, the carrier being soluble in photographic baths and the dye having a tendency to stain permanently the surface of the support, the carrier constituting a layer insulating said surface from the dye.

2. A photographic film comprising a light transmitting, flexible support, a photographically sensitive layer on one surface thereof and a halation reducing backing on the other surface thereof, said backing comprising a water permeable layer and, directly applied to the surface thereof, a dye having a tendency to stain permanently the surface of the support, the water permeable layer insulating the surface from the v dye.

acaaeeo t, A photographic film comprising a light transmitting, flexible support. a photographically sensitive layer on one surface thereof and a halation reducing backing on the other. surface thereof, said backing comprising a water permeable layer carrying directly applied to the surface thereof a dye which is soluble in a solvent that attacks the material of the support but not of the backing layer.

fl. A photographic film comprising a light transmitting, flexible support; a sensitive gelaltine emulsion on one surface thereof and a halation reducing backing on the other surface thereof, said backing comprising a layer of material which is removable in the photographic baths and carrying at its outer surface a dye which is insoluble in water but soluble in a solvent which attacks the material of the support but not of the backing and which does not tend to stain gelatine.

5. A photographic hlm comprising a support `of a cellulosiccomposition, a sensitive emulsion on one surface thereof, and a non-halation backing on the other surface thereof, said backing comprising a layer of material permeable to but v'insoluble in water and soluble in ordinary photographic baths and carrying directly applied to the surface thereof a dye which is water insoluble, but soluble in a solvent that attacks the material of the support but not of the backing layer.

6. A photographic film comprising a light-` transmitting, dexible support, a sensitive emulsion on one surface thereof, and a halationreducing backing on the other surface thereof, said backing comprising a colloidal'layer of a protein which is permeable to but insoluble in vvater and soluble in an alkali solution and carrying directly on its outer surface a dye which is insoluble in Water, but soluble in a solvent which attacks the material of the support but not of the backing.'

7. A photographic ilm comprising a lighttransmitting, ekible support, a sensitive emulsion on one surface thereof and a halation-reduclng backing on the other surface thereof, said backing comprising a colloidal layer of a casein which is permeable to but insoluble in Water and soluble in an alkali solution and carrying applied directly to the outer surface thereof a dye which is insoluble in water but soluble in a solvent which attacks theV material of the support but not of the backing.

8. A photographic film comprising a support of cellulosic composition, a sensitive emulsion on one surface thereof, and a non-halation backing on the other surface thereof, said backing comprising a layer soluble in water or the regular developing baths, and carrying applied directly to the outer surface thereof a dye which is insoluble in Water and the regular developing baths, but soluble in a solvent which may attack the material of the support, but not of the backing layer.

9.v The method of rendering' free from hala tion a photographic film having a light-transmitting support susceptible to certain solvents that comprises applying to said support a layer that is permeable to water, removable in ordinary photographic baths, and unaffected by said certain solvents, vapplying to said layer a dye in solution in one of said 'solvents 'whereby said layer prevents the dye, solution from reaching and staining said support whereby there may be used for anti-halation purposes dyes that otherwise would be unavailable because of their tendency to stain thesupport.

10.The method of reducing lialation in a photographic nlm having -a light-transmitting support susceptible to certain solvents that cornprises applying to said support a layer of a protein that is permeable-to but not soluble in water, but which is soluble in ordinary photographic baths, applying to said layer a dye in solution in a solvent that does not affect said protein but which does attack the support.

1i. The method of reducing halation in a` photographic lm having a light-transmitting cellulosic support susceptible to certain solvents that comprises applying to said support a layer of casein 'which is soluble in an alkali solution and then applying to said casein layer a solution of dye in a readily evaporative solvent that ,does not aHect the casein but which is capable of attacking the material of the support.

' ALFRED D. SLACK. 

